Telecoil systems are used in public buildings such as museums, churches, train stations, and lecture halls, commercial buildings, offices, residential houses, and apartments to provide audio services to allow users to hear the audio sound provided by the telecoil systems without letting the users hear unwanted amplified environmental noises. However, to provide audio services of the telecoil system to the public, the public buildings or commercial buildings need to provide telecoil devices to people who want to exploit the telecoil systems.